1. Field of the Invention
The present invention relates generally to optical fiber connectors and, more particularly, to optical fiber connectors adapted for field installation.
2. Technical Background
Optical fibers are widely used in a variety of applications, including the telecommunications industry in which optical fibers are employed in a number of telephony and data transmission applications. Due, at least in part, to the extremely wide bandwidth and the low noise operation provided by optical fibers, the use of optical fibers and the variety of applications in which optical fibers are used are continuing to increase. For example, optical fibers no longer serve as merely a medium for long distance signal transmission, but are being increasingly routed directly to the home or, in some instances, directly to a desk or other work location.
With the ever increasing and varied use of optical fibers, it is apparent that efficient methods of coupling optical fibers, such as to other optical fibers, to a patch panel in a telephone central office or in an office building, or to various remote terminals or pedestals, is required. However, in order to efficiently couple the signals transmitted by the respective optical fibers, an optical fiber connector must not significantly attenuate or alter the transmitted signals. In addition, the optical fiber connector must be relatively rugged and adapted to be connected and disconnected a number of times in order to accommodate changes in the optical fiber transmission path.
In order to provide the desired signal transmission characteristics, a number of optical fiber connectors have been developed which are mounted to the end portion of an optical fiber during a factory assembly process. By mounting the optical fiber connector to the optical fiber and/or optical fiber cable (hereinafter optical fiber) during an assembly process at the factory, the assembly of the optical fiber connector can be standardized such that inconsistent assembly and other problems associated with the field installation of the connector are avoided.
However, the factory installation of optical fiber connectors is not altogether satisfactory for every application. In particular, the factory installation of optical fiber connectors does not customize the installation process to account for the myriad of design variations experienced in the field. For example, by installing optical fiber connectors to the end portion of an optical fiber at the factory, the length of the connectorized optical fiber is fixed, thus requiring excess length and coiling to insure sufficient length for all applications. In addition, in many instances, it is desirable to cut a length of optical fiber into a plurality of shorter lengths of optical fiber, each of which must be individually connected, such as by an optical fiber connector, to another optical fiber or to a patch panel or other type of terminal. However, the respective lengths of the shorter optical fibers cannot generally be determined until the optical fibers are installed in the field. Thus, in this instance, the requisite optical fiber connectors cannot be mounted to the fibers at the factory prior to installation of the optical fiber. Still further, it is desirable in many instances to package and ship optical fiber prior to the installation of the optical fiber connectors since the optical fiber connectors generally have a greater diameter than the respective optical fiber, and may unnecessarily complicate the packaging and shipping of the optical fiber.
Consequently, several optical fiber connectors have been developed which can be mounted to the end portion of an optical fiber in the field once the particular application of the optical fiber has been determined. For example, U.S. Pat. No. 5,040,867, which issued Aug. 20, 1991 to Michael de Jong et al. and is assigned to the assignee of the present invention, discloses an optical fiber connector adapted for installation in the field. One embodiment of the optical fiber connector of U.S. Pat. No. 5,040,867 is the Camlite® connector which is also manufactured and distributed by Coming Cable Systems LLC.
The Camlite® connector includes a lengthwise extending ferrule defining a longitudinal bore therethrough attached to a V-groove splice with a camming means for securing a fiber in the splice. A short length of optical fiber, typically termed an optical fiber stub, is disposed in the bore of the ferrule and extends into the V-groove splice. In the field, the end portion of an optical fiber, typically termed the field fiber, to which the optical fiber connector is to be connected, can be inserted in the V-groove splice from the end opposite the ferrule. Due to the precise alignment of the longitudinally extending V-groove within the Camlite® connector, the end portion of the field fiber is aligned with the optical fiber stub and thereafter held in place by activating the camming means.
The Camlite® connector can also include a crimp tube mounted to the end of the V-groove opposite the ferrule such that the field fiber extends therethrough. By compressing the crimp tube radially inward so as to contact the buffer, sheath or jacket of the field fiber cable, the field fiber is fixed in position relative to the ferrule and the aligned optical fiber stub. The ferrule of the Camlite® connector can, in turn, be disposed within any of the standard connector housings. For example, the ferrule of the Camlite® connector is compatible with and can be mounted within an FC, ST or SC connector housing. The resulting Camlite® connector can then be connected, such as with an adapter or coupling sleeve, to the end portion of another optical fiber which also has an appropriate connector mounted to an end portion thereof. Alternatively, the resulting Camlite® connector can be connected to a patch panel, remote terminal or pedestal.
While the Camlite® connector was a great advance in the art, the drive to miniaturize optical connectors continues unabated. This has required constant innovation, most particularly in the area of field installable connectors such as the MU connector. Prior art MU offerings have been limited to either plug and play pre-terminated cable assemblies or epoxy and polish connectors. Plug and play solutions, that is, pre-terminated cable assemblies, are simple to field install, but are expensive and require the exact length of the fiber run to be known prior to manufacture, or require storage of slack coils of optical fibers upon installation. Epoxy and polish type connectors are suitable for all applications (including back of panel, transceiver, jumper applications) but require specialized equipment (such as polishers and ovens) and labor intensive processing (curing, polishing). Field installable connectors offer an advantage over both the plug and play solution and the epoxy and polishing connectors in that they are less expensive than the plug and play solution and do not require the specialized equipment or labor intensive processing associated with the epoxy and polish connectors. The present invention offers the advantages of a field installable connector packaged for ease of assembly in a small form MU connector envelope.